According to thegeographical features, the mainland of United States can be divided into 8 regions. They are the Atlantic Plain, the Appalachian Highlands, the Interior Plains, the Interior Highlands, the Rocky Mountain System, the Intermontane Plateaus, the Pacific Mountain System, and the Laurentian Uplands. Next, we’ll see the features of these regions one by one.

a.     The Atlantic Plain （大西洋平原）

Along the east coast of North America is a narrowplain. As you travel south, it becomes wider. The coastal plain is low and flat, which stretches over 3,500 km in length from the New York Bight（海湾）southward to the Texas-Mexico border. The central and southern areas are usually covered with shallow water, featuring extensive wetlands and swamps（沼泽）. These swamps are thick with plants and the soil is fertile.

b.     The Appalachian Highlands （阿巴拉契亚高地）

The Appalachian Mountains（阿巴拉契亚山脉） are a chain of wooded mountains in eastern North America, which separate the eastern coastal plain from the Great Lakes and the Midwest. The range is mostly located in the United State but extends into southeastern Canada, stretching from the island of Newfoundland（纽芬兰岛）of Canada all the way to central Alabama（阿拉巴马州）. The Appalachians is one of the oldest continental mountain systems in the world. Compared with the Rocky Mountains in the western North America,the Appalachian are relatively low in height. The average altitude is only 900meters above sea level. And the highest peak, Mount Mitchell（米切尔山）, is a little over 2,000 meters. In parts of the Appalachians, the land is not good for farming,but it is characterized by large and beautiful deciduous broadleaf trees（落叶阔叶林）.

c.     The Interior Plains （内陆平原）

The Interior Plains is a vast area, extending from the Gulf Coast to the Arctic Ocean. Inthe United States, the plains are between the Appalachian Mountains and the Rocky Mountains, and mainly contain two regions, the Central Lowland in theeast and the Great Plains in the west.

The central lowland stretches from the Great Lakes area to central Texas. It has the most fertile land in the world. Corn, soybeans, and wheat are largely planted in this area.

The Great Plainlies west of Mississippi River and east of the Rocky Mountains. A large portion of the country's agricultural products are grown here. The Great Plains are noted for the extensive grassland. Great herds of cattle and sheep are fed on here as well.

d.     The Interior Highlands （内陆高地）

Located between the Rockies and the Appalachians, this mountain region is located in CentralUS. It spans parts of Kansas, Oklahoma, Arkansas, and Missouri. The Interior Highlands region includes two distinct mountain ranges, the St. Francois Mountains and the Boston Mountains. The vegetation cover in this region is dominated by mixed and temperate broadleaf forests. Thee national forests are also present here.

e.     Rocky Mountain System （落基山脉）

In the west of the Interior Plains, the Rocky Mountains cover a large portion of the western United States, extending from Canada and stretching to Mexico and further south. Compared to some of the other great mountain ranges, the Rockies generally contain fairly mild slopes（斜坡）and wider peaks. But there is no doubt that this region is the highest area in the country, with an average elevation（海拔）of over 4,000 meters. And the tallest peak is called Mount Elbert, located in Colorado（科罗拉多州）at 4,400 meters.

The Continental Divide（大陆分水岭） can be found here. This is the main watershed boundary of the North America. On one side of this great divide, all rivers flow west to the PacificOcean. On the other side, the rivers flow east to the Atlantic Ocean. The Rocky Mountains are notable for some of the most spectacular scenery in the world, such as the breathtaking sunsets, glaciated valleys（冰川谷）and pristine（原始的）forests, which attract visitors forsports and vacations.

f.      Intermontane Plateaus （山间高原）

West of the Rockies are two great plateaus: the Columbia Plateau （哥伦比亚高原） in the north and the Colorado Plateau（科罗拉多高原）in the south, with the Great Basin in between.

The Columbia Plateau is largely formed by ancient lava（熔岩）flows, while the Colorado Plateau is mainly made up of desert, with scattered areas of forests.

In the southwest corner of the Colorado Plateau lies the Grand Canyon（大峡谷）. It’s a steep-sided canyon carved by the Colorado River, with a maximum depth of 1,800 meters, and it’s considered as one of the Natural Wonders of the World.

The Great Basin（大盆地） covers much of the inland western United States. A number of ancient salty lakes can be found here, including the famous Great Salt Lake of Utah. This land receives little rainfall, and much of it is desert. Due to these reasons, the Great Basin remains one of the least populated areas in the country. The Death Valley（死亡谷） is on the western edge of this region. With 200 km long and 86 kmbelow the sea level, the Death Valley is the lowest point and hottest place in the country.

g.     The Pacific Mountain System

Farther west, along the coast, stands another great mountain system, the Pacific Coastal Rages, including Cascade ranges（喀斯喀特山脉）and the Sierra Nevada（内华达山脉）. Different from the low Atlantic coast, the Pacific coast is hilly and has dynamic landforms, such as California’s white sand beaches in the south, and rocky coasts of Washington in the north. The Cascades consist oflargely volcanic mountains, which are shown prominently from the surrounding landscape. The Sierra Nevada, further south, is a high, rugged, and dense mountain range. It contains the highest summit in the contiguous（毗邻的）48 states, Mount Whitney, with an elevation of 4,421 meters.

h.     Laurentian Upland （劳伦高地）

The Laurentian Upland is s basically a part of the Canadian Shield （加拿大地盾）that extends into the northern part of the US. The Canadian Shield has the shape of a giant shield. It stands mainly in Canada, extending south into the Great Lakes area in the northern United States. This is a large area of rocky hills covered withforests.

i.       Alaska and Hawaii

Alaska lies in the northwestern corner of North America, stretching southward from the Arctic Ocean（北冰洋） to the Pacific. Alaska convers more than 1,700,000 km², making it the largest of the 50 statesand more than twice the size of Texas, the second largest state. It consists ofthe mainland the Aleutian Islands, which form one of the longest volcanicisland chains in the world. Alaska is known as a world full of glacier（冰川）, waterfalls and lakes. The main agricultural output in this place is seafood.

    Hawaiiis situated in the central Pacific Ocean, about 3,200 km away from the mainland of the United States. It consists of a long chain of islands, including 8 mainislands and  a hundred atolls（环状珊瑚岛）and smaller islands. The Hawaiian Islands are volcanic, but only the largest Island of Hawaii has active volcanoes. It’s also popular as a tourist destination for people from East Asia and the mainland United States.